Enzyme site-specific changes in hepatic microsomal fatty acid chain elongation in streptozotocin-induced diabetic rats.
The hepatic microsomal fatty acid chain elongation of palmitoyl-CoA and gamma-linolenoyl-CoA was diminished by 40-50% in male Sprague-Dawley rats made diabetic for 2 and 4 weeks following the intravenous administration of a single dose (65 mg/kg) of streptozotocin. Analysis of the activities of the four enzymatic components showed that only one enzyme, the condensing enzyme, which catalyzes the initial and rate-limiting step in chain elongation, was altered by the diabetic state. Both chain elongation and condensation activities were depressed to the same extent, whereas beta-ketoacyl-CoA reductase, beta-hydroxyacyl-CoA dehydrase and trans-2-enoyl-CoA reductase activities were the same as the values obtained with non-diabetic controls. 2 week administration of 10 units of insulin per day to rats which were diabetic for a 2-week period resulted in the reversal of the reduced palmitoyl-CoA elongation and condensation activities to control values. However, neither the condensation nor the elongation of gamma-linolenoyl was reversed by the insulin treatment. These results support the notion of multiple condensing enzymes or chain elongation systems.
Suneja
S K
SK
Department of Pharmacology, University of Connecticut Health Center, Farmington 06032.
Osei
P
P
Cook
L
L
Nagi
M N
MN
Cinti
D L
DL
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D010171:Palmitoyl Coenzyme A / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000214:Acyl Coenzyme A; D005227:Fatty Acids; D010171:Palmitoyl Coenzyme A; C026562:linoleoyl-coenzyme A; D009249:NADP